Psalms 16:4
Their sorrows shall be multiplied that hasten after another god: their drink offerings of blood will I not offer, nor take up their names into my lips. Their sorrows shall be multiplied that hasten after another god: their drink offerings of blood will I not offer, nor take up their names into my lips.
Psalm 16 sets forth the character of those who possess the character of Christ and represent Him in the world. To hasten after another god is to turn away from God and to be unfaithful to Him. Those who do this heap multiplied sorrows upon themselves, bringing upon themselves sorrow and judgment.
In the setting of the day of the Lord this describes those who profess to know God yet have broken His covenant. They are those who conceal sin and follow unrighteousness. They are those who follow other gods. Because of this they are unready for the day of the Lord and will be unable to stand before His judgment.